Ringtail Surgeonfish - Acanthurus blochii

Ringtail Surgeonfish (Acanthurus blochii)

The Ringtail Surgeonfish is a large and active marine tang recognised for its streamlined body, subtle blue-grey to brown colouration and distinctive pale ring around the base of the tail. A strong swimmer with a constant need to graze and explore, this species requires a spacious, mature aquarium with extensive open swimming room and established rockwork. Generally reef safe but increasingly territorial as it matures, it is best suited to experienced marine aquarists with large systems.

Common Name:
Ringtail Surgeonfish, Ringtail Tang

Scientific Name (Latin):
Acanthurus blochii

Maximum Size:
Approximately 45 cm

Water Type:
Marine

Origin / Natural Habitat:
The Ringtail Surgeonfish has a broad Indo-Pacific distribution and is associated with coral reefs, lagoons, channels and outer reef slopes.

Adults are typically found in open reef environments with strong water movement and extensive swimming space, while juveniles may occur in somewhat shallower or more sheltered areas.

Water Parameters:
Temperature: 24–26°C
pH Range: 8.1–8.4
Salinity: SG 1.024–1.026
Nitrate: Low and stable
Ammonia/Nitrite: 0 ppm

Temperament:
Semi-Aggressive

The Ringtail Surgeonfish is generally peaceful towards unrelated reef fish but can become territorial towards other tangs, especially similarly shaped Acanthurus species.

It is usually best maintained as the only large Acanthurus tang unless the aquarium is exceptionally spacious and introductions are carefully managed.

Diet:
Herbivore / Algae Grazer

The Ringtail Surgeonfish naturally spends much of its time grazing algae and associated organic material from reef surfaces.

In the aquarium, provide regular access to dried nori, marine algae sheets, spirulina-based foods, quality herbivore pellets and marine flakes.

A varied diet can also include occasional frozen mysis and other marine foods, but plant-based foods should remain the foundation of its long-term diet.

Minimum Tank Size:
Approximately 900 litres

Its large adult size and highly active swimming behaviour mean the Ringtail Surgeonfish requires substantial horizontal swimming space together with mature rockwork for grazing and shelter.

Behaviour & Activity:
The Ringtail Surgeonfish is an energetic daytime swimmer that spends much of its time cruising through open water and grazing across rockwork.

Provide extensive unobstructed swimming areas together with secure reef structure and sheltered spaces where the fish can retreat.

Strong circulation and excellent oxygenation are especially important for this active species.

Reef Safe:
Reef Safe

The Ringtail Surgeonfish is generally considered reef safe and does not normally damage healthy corals, clams or established ornamental invertebrates.

Its grazing behaviour can be useful in large reef aquariums by helping control nuisance algae and maintaining cleaner rock surfaces.

Special Requirements or Care Notes:
This species should only be purchased with its substantial adult size and long-term space requirements fully considered.

Provide a large, mature marine aquarium with strong biological filtration, high oxygen levels and extensive open swimming room.

Regular access to marine algae is essential even where natural grazing is available.

Like other surgeonfish, the Ringtail Surgeonfish possesses sharp defensive spines near the base of the tail, so care should be taken during handling and aquarium maintenance.

Avoid keeping it with highly aggressive tankmates or multiple large tangs unless the aquarium provides exceptional space.

Surgeonfish can be susceptible to external parasites and transport-related stress, so careful acclimation, quarantine and consistently stable water chemistry are strongly recommended.

Suitable for:
Experienced

Availability:
Availability can vary depending on season, collection area and supplier.

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Please note that Mother Nature is a wonderful thing, and variation in patterns and colours will occur — that is part of the unique beauty of these animals.